In the packaging industry, work is constantly in progress on opening arrangements for improving opening facility, pouring properties, sealing and various types of protection against unauthorized opening of the package. The type of package which is manufactured from a laminate consisting of a paper or cardboard core with thermoplastic and possibly aluminium foil can be produced from a continuous material web or from individual blanks. When a continuous material web is employed, the material web is formed into a tube which is filled with the liquid contents intended for packing, is sealed and cut off into individual packages and is then finally formed into a finished carton or package. The blanks consist of ready-folded and jointed carton blanks which are filled and thereafter sealed and finally formed.
Providing these liquid packages with outer plastic devices is known in the art, for instance from Patent Specification WO 90/14280. These outer plastic devices can be provided with pouring spouts and different types of seals. In order to open the package provided with such a plastic device, various methods have been proposed in the patent literature. The simplest method is a perforation which is forced down using the thumb. This method is unhygienic and there is a risk of spillage when the package is completely filled. Another method is that a portion of the outer plastic device is urged down into the package on opening. In such instance, there is the risk that fibres from the packaging laminate accompany the portion of the plastic device down into the contents of the package and contaminate the enclosed liquid food.